Protein requirements

For very serious strength training it's a general rule that your daily diet includes approximately 1g of protein per pound of body fat spread between 3-6 meals a day (when strength training I normally do 3-4 shakes a day, one immediately when I wake up, one an hour or so before bed, and in between meals as snacks.) For less serious training you of course won't need as much, but that just gives you a general concept of how much protein you should have in your diet if you're trying to build muscle!

Specific timing of drinking the protein shakes is more or less irrelevant as long as it's more or less equally spread throughout the day, and doesn't hinder your exercise.

Protein shakes really are expensive, but I personally think they're worth it when strength training because the protein/carb ratio is unbeatable. If you're buying the shakes by themselves I would suggest purchasing the powdered kind and mixing it with milk (1 cup of milk adds around 8g of protein alone, which is like an added bonus).

Also, if you happen to be having trouble getting enough carbs in each day to give you the energy to do your strength training I would suggest blending banana, milk, and protein mix (I use banana flavor) to give a well balanced shake.

If shakes are just way too expensive for you the only source of cheap protein I can think of is processed meat (i.e. hotdogs, spam, etc.) Though an adverse problem with these is the sodium content.